1. Field of the Invention
This invention generally relates to a method for automatically removing strobe for a digital image capture device, and more particularly to a method for automatically removing strobe for a digital image capturer embedded in a mobile communication apparatus and an apparatus thereof.
2. Description of Related Art
Digital image capturer plays an indispensable role in the modern era. Not only it can used to record activities of our daily life, it also can collect evidence. A digital camera is a classic example of a digital image capturer.
Another important electronic product in the modern era is mobile communication devices. Because of the mobility of mobile communication devices and the high demands of consumers on communication devices, more and more people are using mobile communication devices. Among the different kinds of mobile communication devices, mobile phone is a classic example of a mobile communication device.
As technology advances and consumers desires to spend less, there is a trend toward integrating digital image capturer and the mobile communication device. For example, most of the new mobile phones on the market have built-in cameras. Some of them even provide digital camcorder functions. However, those digital image capturers have to resolve the issue of matching the light source frequency when capturing (or sampling) the image.
Generally, when taking a picture in an indoor environment, the light source will be provided by a lighting equipment with the AC power source. The brightness of the light source provided by the AC power lighting equipment generally changes with the change of the AC voltage. When the AC voltage is at its peak, the brightness of the light source is the highest; however, when the AC voltage is at its bottom, the brightness of the light source is the lowest. In other words, the brightness of the light source provided by the AC power lighting equipment alternates between the peak and the bottom. This is so-called strobe. For example, the AC frequency in Taiwan is 60 Hz. Hence, the period of the light source T is 1/F (= 1/60=0.017 second). Although a naked eye cannot tell the change of brightness in such short time, when the digital image capture device takes a picture, flickerings in the picture is resulted due to the change of brightness. To mitigate the effect of strobe, the exposure gain needs to be adjusted based on the corresponding external environment to obtain an uniform brightness. Therefore, the digital image capturer has to be adjusted based on the AC voltage frequency (generally 60 Hz or 50 Hz) of the place where the picture is taken.
Currently, there are two solutions to remove the strobe for the digital image capture. The first solution uses a predetermined match circuit based on the target market. However, the predetermined match circuit cannot be adjusted. If the digital image capture device is sold in an area with a 50 Hz AC voltage frequency (e.g., Europe) but the user brings it to the area with a 60 Hz AC voltage frequency (e.g., Taiwan), flick is generated due to the strobe. Another solution provides an option to manually adjust the related parameters and thus has more flexibility. However, manual adjustment is inconvenient to the user. In addition, the user may improperly adjust the parameters, which renders this function useless.